Breast milk contains hormones of peptide character, but very little is known about their role in suckling neonates. The importance of this question is stressed by the fact that many of these hormones are not detectable in infant feeding formulas. The purpose of the present application is to evaluate (using suckling and weanling rats as the experimental mode) gastrointestinal processing of epidermal growth factor and prolactin, the routes of absorption (portal blood vs absorption via lymphatics), as well as delivery and metabolism of orally-absorbed epidermal growth factor and prolactin in selected target organs (i.e., brain, liver lung, skin). The role of the presence of epidermal growth factor and prolactin in milk will be tested further by following development of the gastrointestinal tract and other organs of sucklings by feeding formulas containing known amounts of epidermal growth factor and/or absorption. Finally, the cytoprotective role of epidermal growth factor and prolactin will be tested in an experimental model of necrotizing enterocolitis.